NUMS — Medical & Dental Entry Test
Take the NUMS Physics — Waves, Sound, Optics and Thermodynamics (Set 1): 30 multiple-choice questions (40 minutes) with instant scoring and a full answer…
What this test covers
The first 5 questions of this test, with the correct answer and explanation.
Q1. A body performs simple harmonic motion. Which statement about its acceleration is correct?
Answer: A. It is proportional to displacement and directed towards the mean position
Explanation: SHM is defined by a = −ω²x: acceleration ∝ displacement and always directed towards equilibrium.
Q2. The length of a simple pendulum is made four times greater. What happens to its time period?
Answer: B. It doubles
Explanation: T = 2π√(l/g), so T ∝ √l; √4 = 2.
Q3. A 0.4 kg mass is attached to a spring of constant 40 N m⁻¹ and set oscillating. What is its time period?
Answer: B. 0.63 s
Explanation: T = 2π√(m/k) = 2π√(0.4/40) = 2π × 0.1 = 0.628 s ≈ 0.63 s.
Q4. For a mass–spring oscillator moving in SHM, where is the kinetic energy maximum?
Answer: C. At the mean (equilibrium) position
Explanation: At the mean position the speed is greatest (v = ωA) and potential energy is zero, so KE is maximum.
Q5. A soldier column is told to break step while crossing a suspension bridge. This avoids which phenomenon?
Answer: C. Resonance
Explanation: If the marching frequency matches the bridge's natural frequency, resonance can build up large, dangerous amplitudes.
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Q6. An ultrasound probe emits waves of frequency 2 MHz into soft tissue, where the speed of sound is 1540 m s⁻¹. What is the wavelength in the tissue?
Q7. Why can sound not travel through the vacuum of outer space?
Q8. How does the speed of sound in air depend on the absolute temperature T?
Q9. An ambulance siren of frequency 680 Hz approaches a stationary listener at 20 m s⁻¹. What frequency does the listener hear? (speed of sound = 340 m s⁻¹)
Q10. In a stationary wave, what is the distance between two adjacent nodes?
Q11. A pipe 0.5 m long is open at both ends. What is the frequency of its fundamental note? (speed of sound = 340 m s⁻¹)
Q12. The same 0.5 m pipe is now closed at one end. What is its fundamental frequency? (speed of sound = 340 m s⁻¹)
Q13. A piano tuner strikes a 440 Hz reference fork while a slightly flat string vibrates at 437 Hz. What beat frequency does she hear?
Q14. The sound level near a busy road rises by 20 dB. By what factor has the sound intensity increased?
Q15. In a Young's double-slit experiment, light of wavelength 600 nm passes through slits 0.5 mm apart onto a screen 1.0 m away. What is the fringe spacing?
Q16. For a diffraction grating, which equation relates the slit spacing d, the angle θ of the nth-order maximum and the wavelength λ?
Q17. Polaroid sunglasses can block glare from a wet road. Which property of light does polarisation demonstrate?
Q18. What is the speed of light in a glass lens of refractive index 1.5? (c = 3 × 10⁸ m s⁻¹)
Q19. An endoscope carries light along glass fibres by total internal reflection. If the fibre core has refractive index 1.5 (surrounded by air), what is the critical angle?
Q20. An optometrist prescribes a converging lens of focal length 25 cm. What is its power?
Q21. A short-sighted (myopic) patient cannot see distant objects clearly. Which lens corrects this defect?
Q22. A magnifying glass of focal length 5 cm is used with the final image at the near point (D = 25 cm). What is its angular magnification?
Q23. While 800 J of heat is supplied to the gas in a cylinder, the gas pushes a piston outward and does 300 J of work. What is the change in the gas's internal energy?
Q24. In an isothermal expansion of an ideal gas, which quantity is zero?
Q25. A gas is compressed so quickly inside an insulated cylinder that no heat can enter or leave. This process is:
Q26. An ideal reversible engine takes heat from a furnace at 1000 K and rejects heat to river water at 27 °C. What is its efficiency?
Q27. Which statement is consistent with the second law of thermodynamics?
Q28. For one mole of an ideal gas, how are the molar heat capacities Cp and Cv related?
Q29. If the absolute temperature of a gas is made four times greater, what happens to the root-mean-square speed of its molecules?
Q30. A heat engine of efficiency 40% absorbs 1000 J of heat from the hot reservoir in each cycle. How much heat does it reject to the cold reservoir per cycle?